Pneumatic remote position actuator



March 5, 1963 R. w JENSEN 3,079,898

PNEUMATIC REMOTE POSITION ACTUATOR 2 Sheets-Sheet 1 original Filed Sept.2, 1955 Fig. l

III/I7 EE- m w a 2| INVENTOR.

RA man/0 w JENSEN A TTORNE Y March 5,1963 R.W.JE|-1SEN 3,079,898

I PNEUMATIC REMOTE POSITION ACTUATOR Original Filed Sept. 2, 1955 2Sheets-Sheet 2 Fig.3.

1 N V EN TOR. RA YMO/VD M. JENSEN Mam ATTORNEY United States PatentPNEUMATIC REMOTE PfidlTifiN AtZTUATOR Raymond W. Jensen, Phoenix, Aria,assignor to The Garrett Corporation, Los Angeles, Calif., a corporationof California Original application Sept. 2, 1955, Ser. No. 532,206, nowPatent No. 2,3675%, dated Jan. 6, 15959. Divided and this applicationSept. 29, 1958, Ser. No. 764,637

3 Claims. (Cl. 121-41) This invention relates to a pneumatic remoteposition actuator and more particularly to a pneumatic actuator whichmay be remotely controlled precisely to position and maintain a deviceactuated thereby in position regardless of load changes imposed on theactuator by the de vice.

This is a true division of my application Serial No. 532,206, filedSeptember 2, 1955, entitled Pneumatic Remote Position Actuator, nowPatent No. 2,867,194 dated January 6, 1959.

Pneumatic actuators are generally applicable to a variety of aircraftinstallations wherein a source of high pressure air is readilyavailable. Furthermore, pneumatic actuators may provide very rapidresponse to a control condition and are compatible with a great varietyof environmental conditions found in aircraft.

It has been difiicult to control a pneumatic actuator remotely in orderaccurately to locate it in a desired position, and to maintain itprecisely in such a position under varying loads imposed by a devicebeing actuated or positioned. In addition, it is desirable for such apneumatic actuator to be double-acting under the foregoing conditions. i

It is an object of the invention to provide a pneumatic actuator whichis remotely controlled and which will precisely locate and maintainitself in a certain position regardless of loads imposed by a deviceoperated thereby.

Another object of the invention is to provide a pneumatic remoteposition actuator which is particularly adapted to aircraftinstallations wherein pneumatic forces are employed to actuate heavilyloaded devices requiring rapid and accurate positioning, and whereinvery sensitive feed-back means is required to prevent hunting of theactuator, and to maintain the actuated device in a certain position.

Another object of the invention is to provide a novel pneumatic remoteposition actuator having a very compact arrangement of a linear actuatorand associated feedback mechanism.

Another object of the invention is to provide a doubleacting pneumaticremote position actuator having a novel mechanical locking device forholding the actuator in a desired position regardless of varying loadsthereon and which will lock the actuator in its existing position in theevent pneumatic forces acting thereon fail.

A further object of the invention is to provide a pneumatic remoteposition actuator which employs simple and compact means for remotelycontrolling the actuator accurately to locate and position it tomaintain it in a desired position.

A still further object of the invention is to provide a very simplepneumatic remote position actuator which may be remotely controlled by avariety of devices to operate a pneumatic bleed-off valve.

Other objects and advantages of the invention will be apparent from thefollowing specification, appended claims, and accompanying drawings inwhich:

FIGURE 1 is a partial sectional view of a pneumatic remote positionactuator according to the present invention.

FIG. 2 is a sectional view of a modified pneumatic remote positionactuator in accordance with the present "ice invention and showing partsand portions thereof in elevation;

FIG. 3 is a sectional view of another modified pneumatic remote positionactuator in accordance with the present invention and illustrating partsand portions in elevation; and

FIG. 4 is a sectional view of a further modified remote positionactuator in accordance with the present invention and showing parts andportions in elevation.

The invention relates generally to a pneumatic remote position actuatorwhich is capable of operating heavily loaded devices requiring veryrapid positioning and which must be maintained in a desired position. Inaddition, the invention comprises a novel remote control device andfeed-back mechanism which prevents hunting of the actuator duringpositioning and when there are imposed upon it varying loads from thedevice which it actuates.

Pneumatic remote positioning actuators are particularly adapted toaircraft since they may be operated by compresesd air at high pressurebled from the compressor of the aircraft engine. In general, the presentpneumatic remote position actuator is controlled by a pressure regulatorwhich may be manually adjusted or which may be adjusted by any suitabledevice which is responsive to changing conditions.

As shown in FIG. 1 of the drawings, the invention is arranged to controlthermostatically flow of a relatively hot fluid through a conduit 19 bymeans of a butterfly valve 11 which is carried by a pivoted shaft 12.The shaft 12 is actuated by a bellcrank 13 which is pivotally connectedto an actuator rod 14. The actuator rod 14 is connected to a diaphragm15 having one side exposed to a pressure chamber 16 and the other sidesubjected to the pressure in a chamber 17. An opening 17a allowsunrestricted entry of ambient air into the chamber 17 so that thepressure of the air in that chamber is, at all times, the same as thepressure of the ambient air. A spring 18 tends to force the diaphragm 15toward the pressure chamber 16 and to urge the valve 11 toward closedposition. Connected to the diaphragm 15 is a spring 19 which is alsoconnected to a feed-back valve member 20 which operates to regulatepressure in the chamber 16, as will be hereinafter described in detail.The feed-back valve 20 is connected at its upper end to a diaphragm 21which is biased by a spring 22 in opposition to the pressure in achamber 23 communicating with conduits 24 and 25. An opening 23a permitsthe opposite side of the diaphragm 21 to be subjected at all times tothe pressure of the ambient air.

The conduit 25 is a pressure supply conduit, leading from a source ofhigh pressure (not shown), and having a restricted orifice 26 whichserves as an inlet for the chamber 23. The orifice 26 serves as a flowrestriction having a relatively lesser flow capacity than that of apressure regulator 27 which may be adjusted to vary pressure relief fromthe chamber 23 and to control pressure exerted on the diaphragm 21. Thepressure regulator 27 is provided with a pressure responsive diaphragm28 which communicates with the conduit 24. Fluid pressure conducted bythe conduit 24 acts on the diaphragm in opposition to a spring 29, thetension of which is adjustable by a screw 30 having a manual controlknob 31 fixed thereto. Communicating with the conduit 24 and thepressure receiving side of the diaphragm 28 is a ball valve element 32which cooperates with an opening 33 in a plate 34 fixed to the diaphragm28. In operation, a pressure on the diaphragm 28, capable of forcing thespring 29 to yield, moves the opening 33 away from the ball 32 andpermits fluid in chamber 23 to escape to ambient atmosphere through theconduit 24, opening 33, and a vent 35 in the pressure regulator housing.Thus, the pressure regulator 27 functions to maintain a preselectedpressure in the chamber 23 which acts upon the diaphragm 21 andcompresses the spring 22 correspondingly.

The feed-back valve 20, connected to the diaphragm 21, is a cylindricalstructure having an annular groove 36 which controls flow from chamber16 through a vent passage 37 communicating with the ambient atmosphere.

Communicating with the: pressure supply conduit 25 is a branch conduit38 having a restricted flow orifice 39 which communicates with apressure supply passage 40. passage is arranged to conduct workingpressure to the chamber 16 when the end 41 of -thefeed-back valve 20 ismovedupward by the diaphragm 21 to a position in which the passage 49 ispermitted to? communicate with chamber 16; One end. 42 'of'the grooves36in the valve is ar- 7 ranged to restrict the passage 37 concurrentlywith the further opening of the'passage 40 by the end 41 of the valve20. I

Communicating with the chamber 16 is a tube 42:; which alsocommunicateswith a pressure chamber 43 of a thermostatic valve-44. Positioned in thehousing of the valve 44 is a diaphragm 45 which is responsive on oneside to the pressure in the chamber 43. Fixed to the diaphragm 45 isaball valve element 46 which seats in a ventopening 47 extending throughthehousing wall of the chamber 43. This vent opening 47 communicateswith ambient atmosphere and relieves pressure from the chamberl43'whenthe magnitude. of the; pressureacting on the diaphragm 45 issulficientto compress a spring 48 which tends to oppose the pressure inthe chamber 43 and to maintain the ball valve 46 seated in thevent'opening 47. The housing of the thermostatic valve 44 is providedwith a secon d chamber 49 communicating with the diaphragm 45 at theopposite side thereof fromfth'e chamber 43'. A restricted orificeSQ-intercommunicates with the chambers 43 and 49; The chamber 49'isprovided with a vent opening 5lin which; a ball valveelement '52 isseated normally to controlrelief of pressure from the chamber 49 to avent 58 which communicateswith ambient atmosphere. A spring 53cooperates with telescopically assembled temperathre responsive elements54 and 55 to move the ball valve" element {52" ina direction to open thevent 51 when a predeterminedtemperature is reached. The temperatureresponsive elements and 55 have different coeff cients o fiexpa nsionandtend, under changes in temperature, to provide forlinear actuatipn ofthe ball valve element 52. The-temperature rcsponsiveelernent '55 isformed of mate, rial having a greater coefiicient of expansion than thator the element 54 andis fixed at its upper end and free at its lowerend, so thatan increase in temperature will permitthespring 53 to forcethe element 54 down into the element 55 and move the ball valve element52 into openposition relative to the vent opening 51; Communieating withthe conduit 10 intermediate thevalve 11 and the temperature responsiveelement 55, is a conduit 56' which suppliesarelatively cooler fluidstoforma mixture with the hot fluid'flowing past the valve 11. The temperature ofthe mixture is sensed, by the temperature responsive element 55in order to control modulating operation of the valve 11, as will behereinafter described in detail.

Operation "of; the remote position actuator shown in l of the"drawings'is substantially as; follows.

' The pressure regulator 27; being remotely connected to the operatingmechanism of the actuator, may be manually set to eficcta desired:position of the valve 11 iri'the'ccinduitdm "Iihe manual controlknohtillg may be adjusted in accord mg withyalibrations 5 7. in. orderto establish definite initial, compressionof the spring 22'. Thus, thepressure regulator 27 is adjusted to permit prwessurel above apredetermihed' magu tudet be relieved r fth r s r ch 2 .1fmam ic t tm pvia the conduit 24, opening 33, and vent 35;. When a given pressure,determined by the, pressure regulator Z x st i e h ber u hrr s e ac s nhe di phragm .1 tb. sgm esst 11 324 Upwardmwe g a t. o gtlas. iaphragm.1,. Po tings 11? s ih k. ve

. pressure in the chamber 16, permitting'increased vent as a pressureregulator for the chamber 16. When pres- 7 sure is increased in thechamber 16 by reason of a pressure increase in the chamber 23, thediaphragm 15 moves toward the conduit 10 and urges the valve 11 towardthe open position. When pressure in the chamber 16 moves the diaphragm15 against compression of the spring 18, tension in the spring 19 isincreased. This tension serves as a feed-back force which is exerted onthe feed-back valve 20 acting against the pressure in the chamber 23.Thus, the diaphragm 15, as it nears the desired position called for bythe setting of pressure regulator 2 7, is gradually subjected toslightly reducedpres sureby the pull of spring 19 whereby it reachesapredetermined position without overshooting or hunting. When thetemperature sensed by the temperature responsive element 55 reaches apredetermined value, expansion 0f the temperature responsive;element'55- exceeds that of the element 54, thereby permitting thespring 53 to move the ball valve element 52 away from its seat in thevent 5'1, whereupon pressure in the chamber 49' is vented to atmospherevia a vent opening 58'. As pressure in the chamber 49 is thus reduced,the pressure diflerential across the diaphragm 45 is changed, whereuponthe diaphragm moves the ball valve element 46 away from its seat andpermits pressure to escape from the chamber 43 to ambient atmospherethrough the vent opening 47. By this means, pressure in the chamber-16is reduced, which permits. the spring 18 to move the diaphragm 15 in adirection toward the chamber 16, and the valve 11 toward closedposition.

The thermostatic valve 44 operating independently of the pressureregulator 27 may reduce the flowof high temperature fluid through theconduit-10, thereby reducing temperature of a mixture of fluids from theconduits 10 and 56. The thermostatic valve 44, therefore, serves asa-maximum temperature limiter. It will be understood that the pressureregulator 27, as shown in FIG. 1

of the drawings, serves remotely to position the valve 11 to permit acertain flow condition through the conduit 10;

regulator 27 and actuating diaphragm 15 to. provide modulating controlin accordance was temperature ohangesoccurring in the fluidfiowingthrough' the conduit 10.

It will be understood that when the valve 11 is in partially openposition, flow changes through-he conduit 10 may cause an aerodynamicforce to acton thevalve about the axis of, the shaft. 12,. therebycreating load changes on the diaphragm 15. Such a load change, tendingto move the diaphragm 15 toward' the conduit: 10', will cause thefeed-back valve 20, bymeans of the spring 15!, to move slightlytoward-the diaphragm 15rand reduce flow rqu t p s g 31a d ng P s pp ythrough the. passage 40. When pressure is thus reduced in thechamber 16,the-spring 18 overcomes the opposing force on the. diaphragm. 15. andtends to overcome the torque created by the aforesaid aerodynamic forceon the valve 11. V v

In the event changing aerodynamic forces on-the, valve 11 tend to forcethe diaphragm 15 toward the feed-back valve 20, tension in the spring 19is reduced, which permits pressure inthe chamber 23 to movevthefeed-back valve 20-toward the. spring 22; whereuponvent flow firom thechamber 16 through the passage 37 is reduced and-the pressure supply tothe, c m er 16Vfirom the,passage 40v is increased. Thus, pressure in thechamber 16, acting on the, diaphragm 15, is correspondingly. increased,in

Order to v s m W ens. e e hwhafl 1-2 y: e r e dynamic forces which tendto move the diaphragm 15 to ward the chamber 16.

It will be understood that the various diaphragms disclosed in thedrawings of the present invention may be termed movable walls, sinceequivalent devices, for example, pistons or bellows, may be substitutedtherefor as desired.

In the modification of the present invention shown in FIG. 2 of thedrawings, a pressure regulator 66 is remotely connected to its relatedactuating mechanism by means of a tube 61. The pressure regulator 66 issimilar in construction to the pressure regulator 27, shown in FIG. 1 ofthe drawings, and communicates through the tube 61 with a pressurechamber 62 and a diaphragm 63 disposed in the actuating mechanism. Fixedto the diaphragm 63 are clamp plates 64 and 65 which engage a feed-backvalve 66 and a cooperating spring 67, respectively. A light spring 59tends to maintain the feedback valve 66 in engagement with the plate 64.The feed-back valve 66 is a cylindrical valve member reciprocallymounted in a bore 68 in a housing 69 which also forms part of theenclosure for the chamber 62. The feed-back valve 66 is provided with anannular groove 79 which serves as a regulating valve element to controlpressure delivered from a source of high pressure (not shown) through apressure supply tube 71 to a tube 72 which communicates with a pressurechamber 73 and a diaphragm 74.

Intercommunicating with the pressure supply tube 71 and the pressureregulator tube 61 is an orifice '79, the flow capacity of which is lessthan the venting capacity of the pressure regulator 60, in order topermit the pressure regulator 6% to control pressure in the chamber 62.

Connected to the diaphragm 74 is a rod 75 which may be coupled to adevice to be actuated. Communicating with the chamber 73 is a pressurerelief orifice 76 serving as a vent intercommunicating with pressure inthe chamber 73 and ambient atmosphere. A spring 77 exerts force on thediaphragm 74 tending to oppose pressure in the chamber 73 and alsoserves to actuate the rod 75 in one direction.

The housing is provided with a breather vent opening 74a which permitsambient atmosphere, at all times, to communicate with the diaphragm 74which forms one wall of the chamber 73.

The operation of the modified pneumatic remote position actuator of thepresent invention, as shown in FIG. 2 of the drawings, is substantiallyas follows.

When the device connected to the rod 75 is to be moved to and maintainedin a given position, the pressure regmlator 60 is adjusted to a settingon the calibrations 80 which correspond to such position. The pressureregulator 60 then maintains a predetermined pressure in the chamber 62,and the pressure is impressed on the diaphragm 63. Pressure in thechamber 62, when acting on the diaphragm 63, causes correspondingdeflection of the spring 67 and permits the light spring 59 to move thefeed-back valve member 66 in a direction, permitting the annular groove79 to allow an increase of pressure in the chamber 73. When pressure inthe chamber 73 increases, the diaphragm 74 and rod 75 move toward thefeed-back valve 66, causing compression of the spring 77 correspondingto pressure in the chamber 73. As the diaphragm 74 moves toward thefeed-back valve 66, compression of the spring 67 gradually increases andthereby transmits a feed-back force to the feed-back valve 66. Thisforce gradually increases and opposes control pressure acting on thediaphragm 63, thereby causing the feed-back valve 66 to gradually reducethe increase in pressure in the chamber 73. Pressure in the chamber 73is then prevented from increasing too rapidly and causing the diaphragm7 4 to overtravel or hunt about a desired position as determined by thesetting of the pressure regulator 60.

In the event the device being actuated by the rod 75 imposes a load inthe direction of the arrow A, the spring 67 is slightly compressed,whereupon the diaphragm 63 is moved against pressure in the chamber 62,causing corresponding movement of the feedback valve 66, which thereupontends to restrict fiow through the tubes 71 and 72, causing a reductionof pressure in the chamber 73. This reduction takes place due to thefact that there is a constant relief of pressure from the chamber 73 viathe orifice 76. As pressure is reduced in the chamber 73, the force ofthe spring 77 then reacts against the load imposed by the actuateddevice in a direction as indicated by the arrow A.

In the event the actuated device connected to the rod 75 exerts a forcethereon, in the direction of the arrow B, the diaphragm 74 is slightlymoved away from the diaphragm 63, whereby compressive force of thespring 67 is reduced which permits pressure in the chamber 62 to forcethe diaphragm 63 toward the diaphragm 74. Action of the diaphragm 63 inthis direction causes the feed-back valve 66 to permit an increasedpressure to be conducted, via tubes 71 and 72, to the chamber 73.Increased pressure in the chamber 73 then acts on the diaphragm 74 toresist a load change imposed by the actuated device on the rod 75 in thedirection of the arrow B.

From the foregoing it will be understood that the pressure regulator isemployed to predetermine and control the positioning of an actuateddevice connected to the rod 75. The feed-back valve 66 and the spring 67cooperate with the pressure regulator 60 to maintain the actuated devicein a predetermined position, regardless of loads exerted on the rod bythe actuated device.

In the modified pneumatic remote position actuator of the presentinvention, shown in FIG. 3 of the drawings, a pressure regulator 81 maybe remotely positioned with respect to the actuating mechanism of theinvention. The pressure regulator 81 is similar in construction to thatof the pressure regulator 27, as shown in FIG. 1 of the drawings. Thepressure regulator 81 communicates with a chamber 82 and a diaphragm 83by means of a tube 84. A housing 85 serves as one wall of the chamber'82, while the diaphragm S3 constitutes a movable wall thereof. Fixed tothe diaphragm 83 by means of clamp plates '86 and 86b, is a shaft 87having a bore 88 therein. The plate 86b is engaged by a spring 86atending to exert force on the diaphragm 83 in opposition to prmsure inthe chamber 82.

The shaft 87 is slidably mounted in a bore 89 of the housing 85, andcommuncating with the bore 89 is a pressure supply tube 90 leading froma source of high pressure (not shown). A conduit 89a, as shown, permitsthe same iiuid pressure exerted on the bottom end of the shaft 87 to bemanifest upon the top end of the shaft thus making it responsive only toforces applied to the diaphragm 83. An elongated slot 91intercommunicates with the bore 89 and the tube 90, in order to providecommunication of the tube 99 with an opening 92 in the shaft 87 when itmoves axially in the bore 89. The opening 92 in the shaft 87communicates with the bore 88 thereof. An orifice 93 intercommunicateswith the bore 88 and the chamber 82. Carried in an enlarged portion 94of the bore 88 is a feed-back valve 95. A spring 96 tends to maintainthe feed-back valve in closed position to prevent flow past the feedbackvalve and through an opening 97 which communicates with a chamber 98 atone side of the diaphragm 99. The housing 85 is provided with a ventorifice 100 which communicates with the chamber 98. The diaphragm 99 isclamped between plates 191 and 102 connected to a rod 104, the plate 101serving to actuate a stem 103 of the feed-back valve 95. A springengages the plate 102. and exerts a force tending to oppose pressure inthe chamber 98. The rod 104 may be connected to any device to beactuated, as desired.

The operation of the modified form of the invention,

shown in FIG. 3 of the drawings, is substantially as follows.

When a device to be actuated and positioned is connected With the rod104, the pressure regulator 81, by means of its manual control knob 106,is adjusted to correspond to a desired position of the rod 104 and adevice to be actuated thereby. When the pressure regulator 81 is set toregulate pressure in the chamber 82, such pressure acts on the diaphragm83 in opposition to the force of the spring 86a, thereby slightlycompressing the spring to a certain position. The spring 105 tends toforce the j diaphragm 99 toward the shaft 87 and the vent 100 permitspressure to be relieved from the chamber 98 to atmosphere. As thediaphragm 99 thus tends to follow the shaft 87, it contacts the stem 103of the feed-back valve 95 and gradually opens the valve, permittingpressure to pass through the tube 90, bore 88, and opening 97, into thechamber 98, whereupon pressure builds up in the chamber 98 and graduallychecks movement of the diaphragm motivated by the force of the spring105. The feed-back valve element 95 cooperates directly with thediaphragm 99 and with a valve element seat in the enlarged bore 94,which is controlled by the diaphragm 83. It will be noted that directactuataion of the feedback valve element 95 by the diaphragm 99 providesa very simple arrangement without resilient linkage between the mainactuator diaphragm 99 and the power feed-back valve element 95. Theorifice 93 serves as a restricted supply passage for control pressure tothe chamber 82 and pressure regulator 81 and is in communication withthe chamber 82 at all times.

In the event a load change occurs on a device actuated in connectionwith the rod 104, and tends to force it in a direction as indicated bythe arrow C, the diaphragm 99 may be moved away from the shaft 87. Thespring 96 is then permitted to move the feed-back valve .element 95toward the closed position, whereupon a continuous relief of pressurethrough the orifice 100 reduces pressure in the chamber 98 and permitsthe spring 105 to force the diaphragm in a direction opposite to thearrow C, thereby tending to maintain the rod 104 and the device beingactuated in the desired position.

In the event the actuated device exerts a force on the rod 104 in adirection of the arrow D, the feed-back valve element 95, due to slightdeflection of the diaphragm 99, will be moved toward an open position inwhich it permits an increase of pressure in the chamber 98 which acts onthe diaphragm 99 to .oppose the force brought to bear upon the rod 104in a direction of the arrow D.

Inthe modified remote positioning actuator of the present invention,shown in FIG. 4 of the drawings, a thermostatic pressure regulator 107serves as a remote position controller for the positioning and actuatingmechanism cooperating therewith. The pressure regulator 107 is providedwith temperature sensitive elements 108 and 109 which may be disposed ina conduit 110 'to sense a change in the temperature of iluid passingtherethrough. The coefficient of expansion of the element 109 is greaterthan that of the element 108. The element 109 responds to an increase intemperature which will permit a spring 111 to open a ball valve element112 with respect-to a vent seat 113. When the valve element 112 is open,pressure in the chamber 114 -is vented to atmosphere via a vent 115. Thediaphragm 116 forms a movable wall of the chamber 114 and is providedwith an orifice 117 which communicates with chambers 114 and 118 onopposite sides of the diaphragm 7116. En- ,gaged by the diaphragm 116 isa pressure regulating valve 119 which communicates with a pressuresupply tube 120 and the chamber :118. A spring 121 tends to maintain,thepressure regulating valve 119 in engagement with the diaphragm 1 16.A spring 122 engages the diaphragm 116 and tends to oppose pressure inthe chamber 118 which acts on the diaphragm 116.

Communicating withthe pressure supply tube 120 is a 8 tube-123 leadingto orifices 124 and'125 which-communicate with opposite ends of theactuating cylinder 126 in which a piston 127 is reciprocablypositioned.v The shaft 128 extends into the cylinder 126 and supportsthe piston .127 which is axially slidable thereon. The piston 127 isprovided with a hub portion 129 serving as a slide hearing on the shaft128. Opposite ends 130 and 131 of the piston hub portion are engageablewith piston locking fingers 132 and 133, respectively. These lockingfingers 132 and 133 are secured to the piston by resilient members 134and 135, respectively. The piston 127 is provided with a peripheral bodyportion having a greater axial length than that of the hub portion 129,whereby opposite ends 136 and 137 of the piston are normally closer tothe locking fingers 132 and 133 than are the opposite ends 130 and 131,ends 138 and 139 of the locking fingers 132 and 133, respectively, arenormally held in engagement with the cylinder bore 140 by the resilientmembers 134 and 135, whereby they are frictionally locked in a certainposition in the actuator cylinder 126. The locking fingers 132 and 133at their inner ends 141 and 142, respectively, engage annular grooves143 and 144, respectively. The thrust of the piston 127 is transmittedto the shaft 128 by the hub portion 129, the ends 130 and 131 thereof,after limited travel, engaging the inner ends of the fingers, whichserve :as abutments or stops. 7

The shaft 128 is provided with a passage 145 which communicates with theside of the piston 127 adjacent to the fingers 132 and extends to theoutside of the shaft 128 by means of a port 146. The shaft 128 is alsoprovided with another passage 147 communicating with the other side ofthe piston 127, adjacent the locking fingers 133. This passage isprovided with a port 148 which communicates with the outside of theshaft 128 which is surrounded by a feed-back valve element 149 connectedto a diaphragm 150. The diaphragm 150 is responsive on one side topressure in a chamber communicating with the pressure regulating valve119. The ports 146 and 148 are spaced axially of the shaft 128, whilethe valve element 149 is provided with an annular series ofinterconnected radial vent passages 161 which are adapted to furtheropen one of the ports 146 or 148 while concurrently restricting theother one of them. The spring 162 exerts force on the diaphragm 150tending to slide the valve element 149 axially of the shaft 128 whilepressure in the chamber 160 opposes the spring 162.

The operation of the modification of the invention shown in FIG. 4 ofthe drawings is substantially as follows.

The shaft 128 is connected to a device requiring actuation andpositioning, and the thermostatic valve107 con- -trols the operation ofthe pressure regulating valve 119 in accordance with temperature sensedby the temperature sensing element 109. Actuation and positioning of theshaft 128 are controlled indirect proportion to the degree oftemperature change sensed by the thermostatic element 109. When thetemperature increases in the conduit '110, the element 109 expands to agreater extent than does the element 108, permitting the spring 111 toforce the ball valve element 112 from its seat, whereby the chamber 114is vented to atmosphere via the vent openings '113 and 115. pressure inthe chamber 118 acts to compress the spring 122 and move the pressureregulating valve 119 to restrict flow of high pressure air from the tube120 to .the chambers 118 and 160. The pressure regulating valve 119serves as a feed-back valve .since the spring 121 forces it to followthe diaphragm 116 concurrently reducing pressure in the chambers 118 and160. When the diaphragm 116 is moving toward the chamber 114 and thepressure regulating valve 119 is progressively reducing pressure fed tothe chamber 118, the diaphragm 116 reaches a position at which itstabilizes without undue overtraveling or hunting. Thus, pressure in thechamber 160 acting on the diaphragm 150 is very quickly established inrespectively, of the piston hub. The outer,

When the chamber 114 is thus vented,

9 direct proportion to a temperature increase sensed by the temperatureresponsive element 109. It will be noted that a temperature increasesensed by the temperature sensing element 109 will cause a decrease inpressure in the chamber 169, while a reduction in temperature sensed bythe element 199 will cause an increase in pressure in the chamber 160.It will be understood that pressure downstream of the pressureregulating valve 119 and in the chamber 169 will be reduced due to arestricting operation of the pressure regulated valve 119 and due to arelief of pressure through the orifice 117 and vent openings 113 and115, when the ball valve element 112 has been opened to increase flowthrough the vent passage 113. Converse- 1y, if a decrease in temperatureis sensed by the element 16?, it contracts and forces the ball valveelement 112 to restrict the vent passage 113, thereby slowly permittingpressure to build up in the chamber 114. When this pressure increasesrelative to that in the chamber 118, the spring 122 acts to open thepressure regulating valve 11) for increasing flow to the chambers 118and 160.

When pressure increases in the chamber 160, it acts on the diaphragm 150and compresses the spring 162, thereby moving the feed-back valveelement 149 toward a position in which it restricts flow from the port146 and increases flow through the port 143. The feed-back valve thuscauses a pressure rise on the face of piston 12-7 adjacent to thelocking fingers 132 and a pressure decrease on the face of the piston127 adjacent to the locking fingers 133. This pressure differentialcauses the piston 127, at the end 137 of its body portion, to engage thelocking fingers 133 at their outer ends and release them from thecylinder wall 14! The piston 127 at its hub portion 131) then engagesthe fingers 133 adjacent the annular grove 144 and carries the pistonrod 128 in a direction toward the feed-back valve element 149. When thepiston 127 moves toward the feed-back valve element 149, the lockingfingers 132 are merely dragged behind the piston 127 to a new positon.During movement of the piston rod 128 toward the feed-back valve element149, the ports 146 and 148 move relative to the vents 161 and cause agradual reversal of the pressure differential acting to move the piston127 toward the feedback valve element 149.

When pressure is decreased in the chamber 160, the opposite action ofthe feed-back valve element 149, piston 127, locking fingers 132 and133, and the shaft 128 takes place.

When a balance of forces exists in the cylinder 126 at opposite ends ofthe piston 127, the springs 134 and 135 cause the locking fingers 132and 133 to lock the rod 128 axially of the cylinder 126. The rod 128 isthus prevented from being moved by force exerted by the device actuatedby it. It will be understood that the feedback valve element 149cooperating with the ports 146 and 143 provides for a flow capacitywhich is proportioned relative to that of the orifices 124 and 125, sothat pressure in the cylinder 126 may be quickly increased or reduced ateither end of the piston 127. The feedback valve element 149 responds topressure in the chamber 166, which is directly proportional to themagnitude of a temperature change which is sensed by the temperatureresponsive element 109.

In addition to the locking function of the fingers 132 and 133, it willbe recognized that the feedback valve element 149 will automaticallycompensate for loads which may be imposed axially on the shaft 128 by adevice actuated in connection therewith. In the event the fingers 132and 133 become inoperative and slip in the bore of the cylinder 126, thefeed-back valve element 149 will compensate therefor. If a load isapplied to the shaft 128, in a direction as indicated by the arrow B,and should the shaft 128 respond to the force and move in thatdirection, the port 146 in moving relative to the annular vent 161causes restriction of relief flow from the passage 145; and,consequently, pressure is increased on the end of the piston 127adjacent the fingers 132 which opposes the force applied on the rod 128.If a force is applied to the shaft 128 in the direction of the arrow F,the opposite effect will be accomplished by the feed-back valve element149. A pressure differential axially of the piston 127 is quicklychanged by movement of the ports 1-46 and 148 relative to the feedbackvalve element 149. The pressure differential is quickly created due tothe fact that while one of the ports may be progressively restricted,the other may be opened, or vice versa, depending upon the direction offorce applied to the shaft 128 or the direction of movement of thefeedback valve element 149.

It will be noted that a remote pressure regulator employed in thepresent invention may be a pressure relief type, such as the regulator27, or it may be a pressure supply type, such as the regulator 107.

The structure shown in FIG. 4 0f the drawings, is adapted to theactuation of devices requiring a substantial amount of power to movethem in both directions axially of the rod 128.

It will be understood that further modifications of the invention may belimited only by a just interpretation of the following claims.

I claim:

1. An actuator comprising: casing means forming first and second axiallyaligned chambers separated by a partition; a movable wall in eachchamber dividing the same into working pressure "and reference forcechamber sections, said partition separating said working pressuresections, an increase in pressure in either of the latter sectionstending to move the respective wall away from the other wall; means inthe reference force chamber sections for yieldably opposing movement ofsaid walls by pressure increases in said working pressure sections;means for conducting fluid under pressure to the working pressuresections of said chambers, said casing being provided with a restrictedvent permitting a continuous bleed from the working pressure section ofsaid first chamber to a region of reduced pressure; and feedback valvemeans in said fluid conducting means and connected with the movable wallin said second chamber, said feedback valve being operative to controlthe admission on fluid under pressure from a source thereof to theworking pressure section of said first chamber, said feedback valvehaving two parts one of which is projected through said partition foroperative engagement by the movable wall in said first chamber, theother part of said feedback valve being movable by the movable wall inthe second chamber.

2. An actuator comprising: casing means forming first and second axiallyaligned chambers separated by a partition; a movable wall in eachchamber dividing the same into working pressure and reference forcechamber sections, said working pressure sections being adjacent to andon opposite sides of said partition; spring means disposed in saidreference force chamber sections, said spring means being operative tomove said walls toward one another; means for conducting fluid underpressure to the working pressure sections of said chambers, said casingbeing provided with a restricted vent permitting a continuous bleed fromthe working pressure section of said first chamber to a region ofreduced pressure; valve means in said fluid conducting means andconnected with the movable wall in said second chamber, said valve meansbeing operative to control the admission of fluid under pressure from asource thereof to the working pressure section of said first chamber,said valve means having a part projected through said partition formovement by the movable wall in said first chamber to open said valvewhen either of said walls is moved by said spring means; and means forselectively varying the pressure in the working pressure section of thesecond cham ber.

3. An actuator comprising: casing means forming first and second axiallyaligned chambers separated by a parti- ,tion; a movable wall in eachchamber dividing thesame into working pressure and reference forcechamber sections, said working pressure sections being adjacent ,to andon opposite sides of said partition; spring means disposed in saidreference force chamber sections, said spring means being operative tomove said walls toward one another; means for conducting fluid underpressure to the Working pressure sections of said chambers, saidconducting means having a restricted communication with the workingpressure section of said second chamber, said casing being provided witha restricted vent permitting a continuous bleed from the workingpressure section ,of said first chamber to a region of reduced pressure;valve means in said fluid conducting means, said valve means beingoperatively associated with the movable walls in said first and secondchambers and responsive to relative movement between said movable wallsto control the admission of fluid under pressure to the working pressureReferences Cited in the file" of this patent UNITED STATES PATENTS1,004,541 Martin Sept. 26 1911 2,220,180 Spitzglass et a1 Nov. 5, 19402,482,291 Rush et a1. Sept. 20, 1949 2,667,150 Coar Ian. 26, 19542,670,716 Worster et a1. Mar. 2, 1954 2,711,158 Leduc June 21, 19552,773,660 Rasmussen Dec. 11, 1956 2,787,253 Boothe Apr. 2, 1957

1. AN ACTUATOR COMPRISING: CASING MEANS FORMING FIRST AND SECOND AXIALLYALIGNED CHAMBERS SEPARATED BY A PARTITION; A MOVABLE WALL IN EACHCHAMBER DIVIDING THE SAME INTO WORKING PRESSURE AND REFERENCE FORCECHAMBER SECTIONS, SAID PARTITION SEPARATING SAID WORKING PRESSURESECTIONS, AN INCREASE IN PRESSURE IN EITHER OF THE LATTER SECTIONSTENDING TO MOVE THE RESPECTIVE WALL AWAY FROM THE OTHER WALL; MEANS INTHE REFERENCE FORCE CHAMBER SECTIONS FOR YIELDABLY OPPOSING MOVEMENT OFSAID WALLS BY PRESSURE INCREASES IN SAID WORKING PRESSURE SECTIONS;MEANS FOR CONDUCTING FLUID UNDER PRESSURE TO THE WORKING PRESSURESECTIONS OF SAID CHAMBERS, SAID CASING BEING PROVIDED WITH A RESTRICTEDVENT PERMITTING A CONTINUOUS BLEED FROM